Frustrating battery depletion

[WannaVulture]

My F25 has experienced battery depletion for over six months. It is presently at the garage for the third time to ascertain the cause of the issue. The initial alteration of the relay ceased the drain, resulting in a noticeable reduction in power consumption. I continue to have the issue of "increased battery usage when stationary," which occurs intermittently without a discernible pattern.The vehicle was returned to a highly regarded independent garage, which was unable to repeat the issue. It has since been referred to an auto electrician, who likewise cannot reproduce the fault. I am now considering the possibility that the automobile remains in an active state while at home, although I am uncertain as to why this occurs. Is there a possibility of Bluetooth interference affecting the system's connectivity or my home Wi-Fi? I possess two inexpensive Bluetooth battery monitors in close proximity on a camper; may these be the source of the issue? I am considering unconventional possibilities; however, what other factors could contribute to it at home? Thank you.

[engrol]

A rapid assessment utilising ISTA on terminal 30 or for wake-up events will precisely identify the module responsible for the wake-up and subsequent drain. If the Indy has not accomplished that, they are more incompetent than esteemed, since they might have also requested a test plan in ISTA and asked you to return a week later, with the reason of the issue documented in a log and resolved by now. Always remember, the designation of a specialist by garages does not inherently confer expertise.

I would not anticipate the auto electrician to possess ISTA readily available.


Within ISTA

Access the Power Management History

Navigate to “Vehicle Information → Control Unit Tree.”

Choose DME, CAS, FEM, or BDC according on your vehicle; typically, the F25 utilises either CAS or FEM.

Access “Power Management” or “Energy Diagnosis” and select “Power Management History.”

This record indicates:

When the car entered a dormant state
Upon awakening, which module initiated the wake-up process (e.g., “Wake-up cause: telematics control unit (TCB)” or “Wake-up cause: key request”)

This is the essential function for diagnosing battery depletion. If a particular module is consistently identified as a wake-up cause, it is the primary suspect.

To execute a testing protocol


Execute an ISTA test plan for "Energy Diagnosis" or "Enhanced Battery Discharge."
You may adhere to the on-screen guided workflow, which will display:

Documented sleep/wake patterns
Modules that inhibited sleep Battery charge log

[WannaVulture]

Thank you for the guidance, Engrol. I possess a copy of ISTA, but I am uncertain about its use; therefore, your guidance has been immensely beneficial.

[engrol]

superb

In that instance, utilise the following as a step-by-step guide to assist you.




One. Initiate ISTA and Establish Connection

Attach your ENET or K+DCAN cable.
Launch ISTA+ (Rheingold).
Proceed to:
Operations → Retrieve vehicle data → Full identification
Allow ISTA to identify the VIN and retrieve the control unit hierarchy.

Two. Conduct a Fault Memory Assessment
Navigation sequence:
Vehicle management → Diagnostics → Fault memory → Retrieve fault memory

Authorise ISTA to scan all Electronic Control Units (oecus).
Search for codes that reference:
“Terminal 30 awakening”
“Sleep mode inhibited”
“Excessive closed-circuit current”
“Elevated battery depletion while stationary”
When a fault text specifies a particular ECU, take note; this typically indicates the module activating the bus.

Three. Access Power Management History (the crucial step)
Navigation sequence:
Vehicle data → Control unit hierarchy → CAS (Car Access System)
↑ Functions → Power Management → Energy Diagnosis / Power Management History

A table will now be displayed as follows:

Date/Time Event Wake-up Reason Remarks
11/10 23:41 Vehicle activated TCB (Telematics) Remote call
11/11 01:03 Vehicle activated IHKA Climate request
Convey it in the following manner:

The “Wake-up cause” column names the control unit that kept the system alive or woke it up.
If a module recurs — for instance, “TCB” or “CAS” — that is your suspect.

Four. Verify Live Current Draw
Navigation sequence:
Vehicle management → Troubleshooting → Functional structure → Body → CAS → Test plan → Power management: Measurement of current in closed-circuit

Subsequently:

Secure the vehicle (simulate key extraction, terminal 15 deactivated).
Allow approximately 25 to 30 minutes.
Observe current draw:
< 50 mA → normal sleep.
> 100–200 mA → something’s awake.

ISTA frequently designates this as "Vehicle not entering sleep mode."

Five. Optional Guided “Energy Diagnosis”
If ISTA presents you with a Test plan for Energy diagnosis or Battery discharge, please pick it.
It automatically walks through:

Battery history (State of Charge, State of Health)
Sleep and wakefulness records
Wake-up counters per module

This test plan can generate a report enumerating the specific oecus responsible for wake-ups.

[engrol]

[WannaVulture]

I will attempt this upon retrieving the car on Friday and inform you of the outcome. If it fails to function, I believe it may be time to exchange it. Thank you once more.